Question:
After I attach a lens to the camera body, my camera seems unable to secure autofocus. This problem is intermittent but affects multiple lenses. Why is this happening?

Answer:
If the problem occurs with every shot taken with every accessory lens, the camera may be broken. However, if the problem occurs sporadically – and chiefly only after attaching a lens – then it is possible the lens(es) may not have been attached properly.

Remove the lens from the camera and look at the silver mount. Nine gold-colored pins are arranged below the mirror in an arc. These pins must make firm contact with the gold-colored touch points on the back of the lens. This happens naturally when the lens is attached properly, but if the lens is not locked into place then one or more pins may not receive sufficient pressure to maintain contact during use.

To attach a lens to the camera body, align the lens attachment mark (red dot) on the camera mount with the alignment mark (raised red knob) on the side of the lens. Then insert the lens into the camera’s body. Rotate the lens clockwise and listen for a click. The click is an audible indication that the lens lock pin has snapped into place on the back of the lens and has secured the lens in the proper position. The lens lock pin is the small silver pin on the lens mount in between the mirror and the lens release button.

Do not press or hold down the lens release button while attaching a lens to the mount. The lens release button forces the lens lock pin to retract into the camera so that the lens can be removed without breaking the pin. If the button is held down while attaching the lens, it may not align with the hole on the back of the lens after the button is released. This will result in a situation in which the lens is attached to the camera mount but is not locked into place. It is possible that this condition will prevent the lens from making and retaining a firm connection to the camera. This will inhibit autofocus and may increase the lag time between shots.

If the camera’s autofocus had been accurate and now seems to be a little off with all lenses, there may be a piece of lint or an accumulation of dust on the autofocus sensor, which is located in the bottom of the mirror box in the camera body. Lint or dust resting on the sensor can confuse the autofocus system, resulting in less accurate autofocus and even autofocus hunting.

The sensor can be cleaned by blowing out the autofocus sensor well with a blower bulb. Do not use “canned air.” The force of “canned air” can blow particles up into the viewfinder system, and if the can is shaken it may spit the fluid in the can into the camera and leave a residue that may require repair. Remove the lens and use the CLEANING MODE in the camera menu to raise the mirror to gain access to the autofocus sensor.